Proton pump inhibitors represented by omeprazole, which suppress secretion of gastric acid for the treatment of peptic ulcer, reflux esophagitis and the like, have been widely used in clinical situations. However, the existing proton pump inhibitors are associated with problems in terms of effect and side effects. To be specific, since the existing proton pump inhibitors are unstable under acidic conditions, they are often formulated as enteric preparations, in which case several hours are required before onset of the effect, and about 5 days to exhibit maximum efficacy by consecutive administration. In addition, since the existing proton pump inhibitors show variation of treatment effects due to metabolic enzyme polymorphism and drug interaction with medicaments such as diazepam and the like, an improvement has been desired.
As pyrrole compounds having a proton pump inhibitory action, patent reference 1 describes a compound represented by the formula:
wherein X and Y are the same or different and each is a bond or a spacer having 1 to 20 atoms in the main chain, r1 is an optionally substituted hydrocarbon group or an optionally substituted heterocyclic group, r2, r3 and r4 are the same or different and each is a hydrogen atom, an optionally substituted hydrocarbon group, an optionally substituted thienyl group, an optionally substituted benzo[b]thienyl group, an optionally substituted furyl group, an optionally substituted pyridyl group, an optionally substituted pyrazolyl group, an optionally substituted pyrimidinyl group, an acyl group, a halogen atom, a cyano group or a nitro group, and r5 and r6 are the same or different and each is a hydrogen atom or an optionally substituted hydrocarbon group.
As pyrrole compounds having a proton pump inhibitory action, patent reference 2 describes a compound represented by the formula:
wherein r7 is an monocyclic nitrogen-containing heterocyclic group optionally condensed with a benzene ring or heterocycle, which optionally has substituent(s), r8 is an optionally substituted C6-14 aryl group, an optionally substituted thienyl group or an optionally substituted pyridyl group, r9 and r10 are the same or different and each is a hydrogen atom, or one of r9 and r10 is a hydrogen atom, and the other is an optionally substituted lower alkyl group, an acyl group, a halogen atom, a cyano group or a nitro group, and r11 is an alkyl group.
As a therapeutic drug for neoplastic diseases or autoimmune diseases, patent reference 3 describes a compound represented by the formula:
wherein r12 is aryl, aralkyl, heteroaryl and the like, r13 is aryl, heteroaryl and the like, and r14 is aryl, heteroaryl, optionally substituted aminomethyl and the like.
As compounds having a proton pump inhibitory action, patent reference 4 describes a compound represented by the formula:
wherein    ring A is a saturated or unsaturated 5- or 6- membered ring group optionally containing, as a ring-constituting atom besides carbon atoms, 1 to 4 heteroatoms selected from a nitrogen atom, an oxygen atom and a sulfur atom, and the ring-constituting atoms X1 and X2 are the same or different and each is a carbon atom or a nitrogen atom,    R1 is an optionally substituted aryl group or an optionally substituted heteroaryl group,    R2 is an optionally substituted alkyl group, an optionally substituted aryl group or an optionally substituted heteroaryl group, and    R3 is a substituent on the ring-constituting atom other than X1, X2 and X3, which optionally has substituent(s) selected from a lower alkyl group, a halogen atom, a cyano group and oxo.
In addition, as a compound having a carbonic anhydrase inhibitory action, patent document 5 describes a compound represented by the formula
wherein A and E are the same or different and each is a carbon atom or a nitrogen atom, when ring-constituting atom X is a carbon atom, Y is a nitrogen atom and Z is a carbon atom, when ring-constituting atom X is a nitrogen atom, Y is a carbon atom and Z is a carbon atom or a nitrogen atom, R1 and R2 are the same or different and each is a hydrogen atom, a halogen atom, a C1-6 alkyl group and the like, R3 is a hydrogen atom, a halogen atom, a C1-6 alkyl group, (CH2)tCN (t is 0 to 6) and the like, R4, R5 and R6 are the same or different and each is a hydrogen atom, a halogen atom, a C2-12 alkenyl group and the like, R7 and R8 are the same or different and each is a hydrogen atom, a halogen atom, (CH2)t(C3-C12)cycloalkyl (t is 0 to 6) and the like, or R7 and R8 optionally form a 6-membered heterocycle.    patent document 1: WO 2006/036024    patent document 2: WO 2007/026916    patent document 3: WO 2004/103968    patent document 4: WO 2007/114338    patent document 5: WO 2008/017932